Pressurized refill container resistant to standing ring cracking

ABSTRACT

Refillable plastic container includes a top portion, a sidewall portion defining an interior and a longitudinal axis and a base portion extending downwardly of the sidewall portion and defining a closed bottom. The base portion has a heel extending downwardly and inwardly of the sidewall portion at an angle relative the longitudinal axis and having a substantially frustoconical shape. A standing ring extends from heel and defines a support surface of the container. A central dome projects upwardly of the standing ring toward the interior. The central dome portion has a convex surface relative the interior.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of International PatentApplication No. PCT/US2019/029267, filed Apr. 26, 2019, which claimspriority to U.S. Provisional Patent Application Ser. No. 62/663,065,filed on Apr. 26, 2018, which are hereby incorporated by reference intheir entireties.

BACKGROUND Field of the Disclosed Subject Matter

The present disclosed subject matter relates to pressurized containers,such as returnable and/or refillable PET carbonated beverage containers,including such containers having a base structure with increasedresistance to deformation.

Description of Related Art

Many polymer containers, such as refillable PET containers, arerepeatedly exposed to caustic washing to clean the container prior torepeated uses. Such caustic washing can involve exposure to causticcleaning agents at elevated temperatures. Additionally, refilling of thecontainers can involve exposure to elevated internal pressures duringthe refilling process. As such, repeated caustic washing and refillingof such containers over time can cause various deformations, such asstress cracking, including in the standing ring of the base portion.Standing ring cracking can allow contaminants to infiltrate the cracksand thus inhibit or prevent thorough cleaning of the container.Additionally, such cracks can grow to create loss of pressurization andleakage of the bottle contents, which can result in complete bottlefailure. Furthermore, cracking can cause whitening or opacity of thestanding ring, which can be aesthetically undesirable and can interferewith contaminant inspection machinery, which can consider a whitened oropacified region to be a contaminant and reject the bottle.

A refillable container must go through a processing “loop” each time thecontainer is reused. The loop generally is comprised of (1) an emptycaustic wash followed by (2) contaminant inspection and productfilling/capping, (3) warehouse storage, (4) distribution to wholesaleand retail locations, and (5) purchase, use and empty storage by theconsumer followed by eventual return to the bottler. The hot causticwash is particularly detrimental to the reuse of a blow molded polyestercontainer. Certain refillable container base geometries have a longerlinear length due at least in part to the hemispherical shape of theheel, which can result in increased stretching of the preform duringblow molding to form the standing ring portion container. As such, thewall thickness of the standing ring can be thinner, and thus moresusceptible to stress cracking due to caustic washing. It therefore isdesirable to provide a container having a standing ring which canincrease resistance to caustic washing yet flexible enough to withstandthe internal pressures from refilling.

SUMMARY

The purpose and advantages of the disclosed subject matter will be setforth in and are apparent from the description that follows, as well aswill be learned by practice of the disclosed subject matter. Additionaladvantages of the disclosed subject matter will be realized and attainedby the devices particularly pointed out in the written description andclaims hereof, as well as from the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the disclosed subject matter, as embodied and broadly described, thedisclosed subject matter includes a container having a top portiondefining an opening, a sidewall portion extending downwardly of the topportion and defining an interior and a longitudinal axis, and a baseportion extending downwardly of the sidewall portion and defining aclosed bottom. The base portion includes a heel extending downwardly andinwardly of the sidewall portion at an angle relative the longitudinalaxis and having a substantially frustoconical shape, a standing ringextending from the heel and defining a support surface of the container,and a central dome extending upwardly of the standing ring toward theinterior, the central dome having a convex surface relative theinterior.

In accordance with another aspect of the disclosed subject matter, abase portion for a container includes a heel extending downwardly andinwardly of the sidewall portion at an angle relative the longitudinalaxis and having a substantially frustoconical shape, a standing ringextending from heel and defining a support surface of the container, anda central dome extending upwardly of the standing ring toward theinterior, the central dome having a convex surface relative theinterior.

It is to be understood that both the foregoing general description andthe following detailed description and drawings are examples and areprovided for purpose of illustration and not intended to limit the scopeof the disclosed subject matter in any manner.

The accompanying drawings, which are incorporated in and constitute partof this specification, are included to illustrate and provide a furtherunderstanding of the devices of the disclosed subject matter. Togetherwith the description, the drawings serve to explain the principles ofthe disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the application will be more readily understoodfrom the following detailed description when read in conjunction withthe accompanying drawings, in which:

FIG. 1 is a side view of an exemplary embodiment of a container havingan exemplary base in accordance with the disclosed subject matter.

FIG. 2 is a cross-sectional side profile view of the container takenalong line 2-2 in FIG. 1.

FIG. 3 is a detailed view of region 3 of FIG. 2, showing the exemplarybase of the container.

FIG. 4 is a cross-sectional side view of the base of FIG. 3 overlaidwith a conventional base of a conventional container shown in dashedlines for purpose of illustration and comparison with the disclosedsubject matter.

FIG. 5 is the side view of the conventional base of a conventionalcontainer of FIG. 4, illustrating selected reference locations inbrackets for purpose of illustration and comparison with the disclosedsubject matter.

FIG. 6 is a cross-sectional side profile view of the base of FIG. 3,illustrating selected reference locations in brackets.

FIG. 7 is a diagram illustrating the wall thickness at the variousreference locations illustrated in FIGS. 5-6 for purpose of illustrationand confirmation of the disclosed subject matter.

FIG. 8A is a side view image of a finite element model of theconventional base of a conventional container for purpose ofillustration and comparison with the disclosed subject matter.

FIG. 8B is a bottom perspective view image of the finite element modelof FIG. 8A of the conventional base of a conventional container forpurpose of illustration and comparison with the disclosed subjectmatter.

FIG. 9A is a side view image of a finite element model of an exemplarybase in accordance with the disclosed subject matter.

FIG. 9B is a bottom perspective view image of the finite element modelof the exemplary base of FIG. 9A in accordance with the disclosedsubject matter.

FIG. 10 is a diagram illustrating the stress concentration in the heelover a range of increasing pressures for a container in accordance withthe disclosed subject matter as compared with a conventional base for aconventional container.

FIG. 11 is a diagram illustrating the stress concentration in thestanding ring over a range of increasing pressure for a container inaccordance with the disclosed subject matter as compared with aconventional base for a conventional container.

FIG. 12 is a diagram illustrating standing ring movement over a range ofincreasing pressure for a container in accordance with the disclosedsubject matter as compared with a conventional base for a conventionalcontainer.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the disclosedsubject matter, an example of which is illustrated in the accompanyingdrawings. The disclosed subject matter will be described in conjunctionwith the detailed description of the system.

The apparatus and methods presented herein can be used for transportingand refilling of perishable or nonperishable liquids. The disclosedsubject matter is particularly suited for packaging, storing, anddispensing beverages, including fruit and vegetable juices, soft drinksor tea or the like.

In accordance with the disclosed subject matter, a container includes atop portion defining an opening, a sidewall portion extending downwardlyof the top portion and defining an interior and a longitudinal axis, anda base portion extending downwardly of the sidewall portion and defininga closed bottom. The base portion includes a heel extending downwardlyand inwardly of the sidewall portion at an angle relative thelongitudinal axis and having a substantially frustoconical shape, astanding ring extending from the heel and defining a support surface ofthe container, and a central dome extending upwardly of the standingring toward the interior, the central dome having a convex surfacerelative the interior.

In accordance with another aspect of the disclosed subject matter, abase portion for a container includes a heel extending downwardly andinwardly of the sidewall portion at an angle relative the longitudinalaxis and having a substantially frustoconical shape, a standing ringextending from heel and defining a support surface of the container, anda central dome extending upwardly of the standing ring toward theinterior, the central dome having a convex surface relative theinterior.

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, serve to further illustrate various embodiments and to explainvarious principles and advantages all in accordance with the disclosedsubject matter. For purpose of illustration, and not limitation,exemplary embodiments of the base and container with the disclosedsubject matter are shown in the accompanying FIGS. FIGS. 1-4 and 6. Thebase and container are suitable for use with a wide variety of liquids.For purpose of illustration only, reference is made to a container for acarbonated beverage. As used herein, the terms “front,” “rear,” “side,”“top,” and “bottom” are used for the purpose of illustration only, andnot limitation.

For purpose of illustration, reference will be made to onerepresentative embodiment of a container having a generally cylindricalshape. FIGS. 1-2 illustrate exemplary embodiments of a representativecontainer having the base of the disclosed subject matter. The examplesherein are not intended to limit the scope of the disclosed subjectmatter in any manner. For the purposes of illustration and notlimitation, reference is made to the exemplary embodiment of a container100 as shown in FIGS. 1-2.

With reference to FIGS. 1-2, for example and as embodied herein, thecontainer 100 generally includes a top portion 101 defining an opening102, a sidewall portion 103 extending downwardly from the top portion101 and defining an interior and a longitudinal axis 107, and a baseportion 111 extending downwardly from the sidewall portion 103 anddefining a closed bottom. The opening 102 can be formed of any suitableor desired configuration. The top portion can further include anunexpanded and substantially amorphous neck finish 104, with externalscrew threads and retaining flange 105. A tapered shoulder 106 canincrease radially in diameter going down towards a sidewall portion 103.The sidewall portion 103 can define an interior and a longitudinal axis107. The base portion 111 of the container 100 includes a heel 108extending downwardly and inwardly from sidewall portion 103 at an angleA relative the longitudinal axis 107, the heel 108 having asubstantially frustoconical shape and reducing in diameter towards astanding ring 109. The heel 108 can extend directly or indirectly fromsidewall portion 103. For example, and as embodied herein, the heel 108can extend directly from the sidewall portion 103.

With continued reference to FIGS. 1-2, the standing ring 109 extendsinwardly from the heel 108 and defines a support surface 110 of thecontainer 100. In some embodiments, the base portion further includes anouter support wall 113 extending between the sidewall portion 103 andthe heel 108. Extending upwardly of the standing ring 109 towards theinterior is a central dome 112 having a convex surface relative theinterior.

As shown in FIGS. 1-2, for example and as embodied herein the container100 generally includes a cylindrical shape with an initial height H,sidewall portion diameter D[SW], a maximum base portion diameter D[BP],and a standing ring diameter D[SR]. The base of the disclosed subjectmatter can be used with containers of a wide variety of shapes andconfigurations. For example, containers according to the disclosedsubject matter can have any suitable shape, including but withoutlimitation, square, rectangular, and elliptical shapes, and can be usedwith the base disclosed herein. For example, and not limitation, asembodied herein, an exemplary container for approximately 2.5 liters ofcarbonated beverage can have an initial height H of approximately 14 toapproximately 15 inches; a sidewall portion diameter D[SW] ofapproximately 4 to approximately 5 inches; a maximum base portiondiameter of approximately 4 to approximately 5 inches and a standingring diameter D[SR] of approximately 2.5 inches to approximately 3inches.

Referring now to FIG. 3, for example and as embodied herein, thecontainer 100 includes a heel 108 extending downwardly and inwardly fromsidewall portion 103 at an angle A relative the longitudinal axis 107.The heel can have any suitable shape. For example, and as depicted inFIG. 3, the heel 108 can have a substantially frustoconical shape, andcan taper in diameter towards a standing ring 109. The angle A can beany suitable angle capable of achieving the desired purpose of thedisclosed subject matter. For example, the angle A can be within therange of about 35 degree to about 45 degrees and in some embodiments,the angle A can be about 40 degrees. In this manner, angle A can reduceor minimize the distance the preform must stretch to reach the standingring 109 of the container 100, which can allow for a greater wallthickness in the standing ring 109 of the container 100. As shown forexample in FIG. 3, and as embodied herein, the standing ring 109 can beconcave relative the interior in transverse cross-section.

With continued reference to FIG. 3, and as noted above, the base portion111 as depicted has a central dome 112 extending upwardly from thestanding ring 109 toward the interior, the central dome 112 having aconvex surface relative the interior. The central dome 112 can extenddirectly or indirectly from the standing ring 109. For example, and asembodied herein, the central dome 112 can extend directly from thestanding ring 109. Additionally or alternatively, the central dome 112can have a substantially hemispherical shape.

For purpose of illustration and comparison with the disclosed subjectmatter, FIG. 4 shows a cross-sectional view of base portion 111 overlaidonto a cross-sectional view of a conventional base portion 111O ofsimilar volume and material of construction. As shown in FIG. 4, and asembodied herein, base portion 111 can have a central dome 112 having aradius of curvature R4, a standing ring 109 having a radius of curvatureR5, and a heel transition portion 114 having a radius of curvature R6.By contrast, the conventional base portion 111O in cross section has acentral dome 112O having a radius of curvature R3, a standing ring 109Ohaving a radius of curvature R2, and a heel 108O having a radius ofcurvature R1. The conventional base portion 111O further includes anexternal gate (not shown in FIG. 4 for the purpose of comparison only).Further, as depicted in FIG. 4, the standing ring 109 of the baseportion 111 can have a radius in plan view of L[N1], while the standingring 109O of the conventional base has a radius in plan view of L[O1].The central dome 112 of the base portion 111 can have depth of L[N2],while the central dome 112O of the conventional base 111O has a depth ofL[O2]. Additional details of an exemplary container base according tothe disclosed subject matter as compared to a conventional base portionfor a container of similar volume and material of construction are setforth in Table 1, below.

TABLE 1 Base Portion 111 Conventional Base Portion 111O R3 (inches)1.654 R4 (inches) 1.372 R2 (inches) 0.14 R5 (inches) 0.10 R1 (inches)1.52 R6 (inches) 0.50 L[O1] (inches) 1.436 L[N1] (inches) 1.35 L[O2](inches) 0.760 L[N2] (inches) 0.850FIGS. 5-7 together illustrate exemplary wall thicknesses of an exemplarybase 111 for a container in accordance with the disclosed subject matteras compared with a conventional base 111O for a conventional containerof similar volume and material of construction for purpose ofillustration and comparison of the disclosed subject matter. FIG. 5shows reference locations [1]-[8] along the center line of aconventional container base portion 111O having a hemispherical heel.FIG. 6 shows reference locations [1]-[8] along container base portion111 in accordance with the disclosed subject matter having afrustoconical heel extending downwardly and inwardly at an anglerelative the longitudinal axis. For purpose of comparison, thecontainers having the base portions of FIG. 5 and FIG. 6, respectively,were made using substantially similar preforms with substantially thesame amount of material and substantially similar blow moldingtechniques. As shown in FIG. 7, for purpose of illustration and notlimitation, the base portion 111 in accordance with the disclosedsubject matter results in a wall thickness in the standing ring 109(shown at reference point 4.5 in FIG. 6) that is greater than the wallthickness in the standing ring 109O (shown at reference point 4.5 inFIG. 5) of the conventional base 111O.

Hence, in accordance with the disclosed subject matter, theconfiguration of the base portion 111 provides for a greater wallthickness at the standing ring 109 as compared to the wall thickness ofthe standing ring of a conventional container formed using asubstantially similar preform with substantially the same amount ofmaterial and a substantially similar blow molding technique as used toform the container having base portion 111. For example and notlimitation, the wall thickness in the standing ring 109 of the baseportion 111 in accordance with the disclosed subject matter results inat least 10% greater than the standing ring 109O of a substantiallysimilar bottle having a conventional base 111O. In certain embodiments,the thickness in the standing ring 109 of the base portion 111 for acontainer 110 weighing 106 grams can be within a range of 2.4 mm to 2.5mm. In certain embodiments, the thickness in the standing ring 109 ofthe base portion 111 for a container 110 weighing 112 grams can bewithin a range of 2.5 mm to 2.6 mm. The increased thickness of thestanding ring 109 of the base portion 111 for a container 110 ascompared to the standing ring 109O of the base portion 111O for acontainer 110O having a substantially similar weight can prevent orinhibit deformation due to increased pressure, such as stress crackingdue to caustic washing and/or refilling. Thereby, the resultingincreased thickness of the standing ring 109 of the base portion 111 fora container 110, as discussed herein, can also allow for a container 110to be made lighter or with less material while maintaining theperformance of a container 110O having a heavier weight.

FIGS. 8A-9B together illustrate the stress due to internal pressure atvarious locations on an exemplary base 111 for a container in accordancewith the disclosed subject matter as compared with a conventional base111O for a conventional container for purpose of illustration of thedisclosed subject matter. FIG. 8A is a side view of a finite elementmodel of a conventional container base portion 111O having ahemispherical heel and FIG. 8B is a bottom perspective view of the baseportion of FIG. 8A, each illustrating the stress due to internalpressure at various locations. FIG. 9A is a side view of a finiteelement model of an exemplary embodiment of container base portion 111in accordance with the disclosed subject matter having a frustoconicalheel extending downwardly and inwardly at an angle relative thelongitudinal axis and FIG. 9B is a bottom perspective view of the baseportion of FIG. 9A, each illustrating the stress due to internalpressure at various locations. The respective containers of thesefigures are otherwise substantially the same. As demonstrated in FIGS.9A-9B, for purpose of illustration and not limitation, the heel 108 ofthe base portion 111 of the disclosed subject matter distributes thestress upwardly along the heel as compared to the conventional base111O.

FIG. 10 depicts a graph of the stress concentration in the heel over arange of increasing pressures for a container in accordance with thedisclosed subject matter as compared with a conventional base for aconventional container for purpose of illustration of the disclosedsubject matter. Particularly, conventional bases of this type are mostprone to failure due to internal pressure along the radiused heel, suchas stress cracking due to caustic washing and/or refilling. As shown inFIG. 10, the embodiment of the disclosed subject generally exhibits lessstress concentration in the heel compared to the conventional base.

FIG. 11 depicts a graph of the stress concentration in the standing ringover a range of increasing pressures for a container in accordance withthe disclosed subject matter as compared with a conventional base for aconventional container for purpose of illustration of the disclosedsubject matter. As shown in FIG. 11, the embodiment of the disclosedsubject matter generally exhibits less stress concentration in thestanding ring compared to the conventional base.

FIG. 12 depicts a graph of the standing ring movement over a range ofincreasing pressures for a container in accordance with the disclosedsubject matter as compared with a conventional base for a conventionalcontainer for purpose of illustration of the disclosed subject matter.As shown in FIG. 12, the embodiment of the disclosed subject mattergenerally exhibits less standing ring movement compared to theconventional base.

Bases and containers according to the disclose subject matter canparticularly useful as a refillable carbonated beverage container ableto withstand repeated refill cycles while maintaining aesthetic andfunctional features. For the purpose comparison, samples each of acontainer having an exemplary base in accordance with the disclosedsubject matter and a container having a conventional base for aconventional container were produced. The containers were made using asubstantially similar preform with substantially the same amount ofmaterial and a substantially similar blow molding technique, and eachwere substantially the same weight. For purpose of illustration andconfirmation of the disclosed subject matter, a test procedure forsimulating and repeating such cycles without crack failure was performedon the produced sample containers, as further discussed below.

Generally, the containers were subjected to a known commercialacceptable caustic wash solution, which was maintained at a desired washtemperature. The containers were submerged uncapped in the wash for adesired amount of time to approximate the time/temperature conditions ofa commercial bottle wash system. After removal from the wash solution,the bottles were rinsed in tap water and then filled with a carbonatedwater solution at a desired pressure to approximate the pressure of acarbonated soft drink container. The containers were then depressurizedand subjected to the same refill cycle (i.e. a loop) until failure. Forpurpose of this test, initial failure was defined as any visual crackobserved in the container wall, and final failure was defined any crackpropagating through the container wall resulting in leakage and pressureloss, such that the container was no longer usable.

It was determined through the aforementioned testing of a number ofsamples of each type of container that the unique base configuration ofthe disclosed subject matter results in an improved and desirableprocessing cycle performance as compared to a substantially identicalcontainer of the same weight and material but with a conventional base.For example, at certain container weights, such as 119 grams, aconventional container withstood an average of 10 refill cycles (i.e.loops) before initial failure when initial failure occurred in the neck,and an average of 17 loops before initial failure when initial failureoccurred in the base. In contrast, the container of the disclosedsubject matter withstood an average of 12.2 loops before initial failurewhen initial failure occurred in the neck, and no failure ever occurredin the base portion. Further, a conventional container withstood anaverage 15.67 refill cycles before final failure when final failureoccurred in the neck, and an average of about 21.25 loops before finalfailure when final failure occurred in the base. In contrast, thecontainer of the disclosed subject matter withstood an average of 19.4loops before final failure when final failure occurred in the neck, andno failure ever occurred in the base portion. Hence, these test resultsdemonstrate that the frustoconical heel as disclosed and as generallyembodied herein can improve resulting container performance by reducingfailure due to internal pressure, e.g., from caustic washing;specifically, the unique base configuration of the disclosed subjectresults in no failure in the base portion before failure of thecontainer as a whole (e.g., failure in the neck portion), as well as anincreased average life or number of loops in the processing cycle beforeinitial and final failures in the neck portion as compared to aconventional container.

The container of the disclosed subject matter can be manufactured by anynumber of suitable methods, as known in the art. For example, and asembodied herein, the container and integral base can be manufactured byconventional blow molding. Exemplary techniques for blow molding acontainer in accordance with the disclosed subject matter are shown anddescribed in U.S. Pat. No. 5,989,661, which is incorporated by referenceherein in its entirety. As is appreciated by one having skill in theart, a variety of known manufacturing and process variations can be usedin accordance with the disclosed subject matter. Additional techniquesfor manufacturing refillable beverage containers are shown and describedin U.S. Pat. Nos. 4,334,627; 4,725,464; and 5,066,528; each of which isincorporated by reference herein in its entirety.

The container and the base can be formed from any suitable materials.For example and as embodied herein, the container and base can be formedof a polymeric material, such as and not limited to, polyethyleneterephthalate (PET). Additionally or alternatively, for example andwithout limitation, the container and base can be formed frompolyethylene naphthalate (PEN) and PEN-blends, polypropylene (PP),high-density polyethylene (HDPE), and can also include monolayer blendedscavengers or other catalytic scavengers as well as multi-layerstructures including discrete layers of a barrier material, such asnylon or ethylene vinyl alcohol (EVOH) or other oxygen scavengers.

While the disclosed subject matter is described herein in terms ofcertain preferred embodiments, those skilled in the art will recognizethat various modifications and improvements can be made to the disclosedsubject matter without departing from the scope thereof. Moreover,although individual features of one embodiment of the disclosed subjectmatter can be discussed herein or shown in the drawings of the oneembodiment and not in other embodiments, it should be apparent thatindividual features of one embodiment can be combined with one or morefeatures of another embodiment or features from a plurality ofembodiments.

In addition to the various embodiments depicted and claimed, thedisclosed subject matter is also directed to other embodiments havingany other possible combination of the features disclosed and claimedherein. As such, the particular features presented herein can becombined with each other in other manners within the scope of thedisclosed subject matter such that the disclosed subject matter includesany suitable combination of the features disclosed herein. Thus, theforegoing description of specific embodiments of the disclosed subjectmatter has been presented for purposes of illustration and description.It is not intended to be exhaustive or to limit the disclosed subjectmatter to those embodiments disclosed.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the disclosed subject matterwithout departing from the spirit or scope of the disclosed subjectmatter. Thus, it is intended that the disclosed subject matter includemodifications and variations that are within the scope of the appendedclaims and their equivalents.

What is claimed is:
 1. A refillable plastic container comprising: a topportion defining an opening; a sidewall portion extending downwardly ofthe top portion, the sidewall portion defining an interior and alongitudinal axis; and a base portion extending downwardly of thesidewall portion and defining a closed bottom, the base portioncomprising: a heel extending downwardly and inwardly of the sidewallportion at an angle relative the longitudinal axis, the heel having asubstantially frustoconical shape, a standing ring extending from theheel and defining a support surface of the container, a central domeextending upwardly of the standing ring toward the interior, the domehaving a convex surface relative the interior.
 2. The container of claim1, wherein the sidewall portion is cylindrical and generally circular inplan view.
 3. The container of claim 1, wherein the base portion furthercomprises an outer support wall extending between the sidewall portionand the heel.
 4. The container of claim 1, wherein the angle of the heelrelative the longitudinal axis is within a range of about 35 degrees toabout 45 degrees.
 5. The container of claim 1, wherein the angle of theheel relative the longitudinal axis is about 40 degrees.
 6. Thecontainer of claim 1, wherein the standing ring is concave relative theinterior in transverse cross-section.
 7. The container of claim 1,wherein the standing ring is arcuate in transverse cross-section.
 8. Thecontainer of claim 1, wherein the standing ring has a radius of lessthan about 1.5 inches in transverse cross-section.
 9. The container ofclaim 1, wherein the standing ring has a wall thickness configured toresist flexing of the standing ring during a sterilization and refillprocess.
 10. The container of claim 1, wherein the standing ring has awall thickness at least 10 percent greater than a wall thickness of thestanding ring of a substantially similar bottle having a radiused heelin transverse cross section.
 11. The container of claim 9, wherein thewall thickness of the standing ring is within a range of about 2.4 mm toabout 2.6 mm.
 12. The container of claim 1, wherein the standing ringextends directly from the heel.
 13. The container of claim 1, whereinthe central dome extends directly from the standing ring.
 14. Thecontainer of claim 1, wherein the central dome has a substantiallyhemispherical shape.
 15. The container of claim 1, wherein the containercan withstand at least 20 refill cycles in a commercially acceptablecaustic wash without failure in the standing ring portion.
 16. Thecontainer of claim 1, wherein the container comprises polyester.
 17. Thecontainer of claim 15, wherein the container comprises a polyestercomprising polyethylene terephthalate (PET).
 18. A base portion for arefillable plastic container having a top portion, sidewall portion, andthe base portion, the base portion comprising: a heel extendingdownwardly and inwardly of the sidewall portion at an angle relative thelongitudinal axis, the heel having a substantially frustoconical shape;a standing ring extending from the heel and defining a support surfaceof the container; a central dome extending upwardly of the standing ringtoward the interior, the central dome having a convex surface relativethe interior.
 19. The base portion of claim 18, wherein the sidewallportion is cylindrical and generally circular in plan view.
 20. The baseportion of claim 18, wherein the base portion further comprises an outersupport wall extending between the sidewall portion and the heel. 21.The base portion of claim 18, wherein the angle of the heel relative thelongitudinal axis is within a range of about 35 degrees to about 45degrees.
 22. The base portion of claim 18, wherein the angle of the heelrelative the longitudinal axis is about 40 degrees.
 23. The base portionof claim 18, wherein the standing ring is concave relative the interiorin transverse cross-section.
 24. The base portion of claim 18, whereinthe standing ring is arcuate in transverse cross-section.
 25. The baseportion of claim 18, wherein the standing ring has a radius of less thanabout 1.5 inches in transverse cross-section.
 26. The base portion ofany of claim 18, wherein the standing ring has a wall thicknessconfigured to resist flexing of the standing ring during a sterilizationand refill process.
 27. The base portion of claim 18, wherein thestanding ring has a wall thickness of at least 10 percent greater than awall thickness of a standing ring of a substantially similar bottlehaving a radiused heel in transverse cross section.
 28. The base portionof claim 26, wherein the wall thickness of the standing ring is within arange of about 2.4 mm to about 2.6 mm.
 29. The base portion of claim 18,wherein the standing ring extends directly from the heel.
 30. The baseportion of claim 18, wherein the central dome extends directly from thestanding ring.
 31. The base portion of claim 18, wherein the centraldome has a substantially hemispherical shape.
 32. The base portion ofclaim 18, wherein the container can withstand at 20 refill cycles in acommercially acceptable caustic wash without failure in the standingring.
 33. The base portion of claim 18, wherein the container comprisespolyester.
 34. The base portion of claim 32, wherein the containercomprises a polyester comprising polyethylene terephthalate (PET).